植物内生放线菌防治西葫芦白粉病的初步研究

以西葫芦白粉病为对象，通过温室盆栽试验和叶盘筛选试验，从50个内生放线菌菌株中筛选出2个防病效果较好的菌株，叶盘筛选试验发现菌株GKSHJA和PR1-8的无菌滤液原液在接种病菌的同时使用防治效果最佳，分别达到60.98%和63.22%。温室人工接种白粉病菌的盆栽试验发现，GKSHJA无菌滤液原液在接种前、接种后24 h喷雾，相对防治效果分别达55.22%和16.44%；菌株PR1-8的相对防效分别为51.94%和24.39%，且GKSHJA和PR1-8无菌滤液的5倍稀释液在接种病菌的同时使用也有一定的防病效果，其病情指数分别比对照降低了27.81%和30.19%。在自然感病的田间试验中，菌株GKSHJA和PR1-8无菌滤液的5倍稀释液对西葫芦白粉病的相对防效分别达到56.33%和69.88%。这些结果表明，菌株GKSHJA和PR1-8作为防治瓜类白粉病的生防菌株，具有开发应用潜力和前景。

Biocontrol of Zucchini Powdery Mildew by Endophytic Actinomycetes

Fifty strains of endophytic actinomycetes were screened in greenhouse pot experiments and leaf-disc tests in lab. Two strains showed stable control effect on zucchini powdery mildew. In the leaf-disc tests, the application of cell free filtrate of strains GKSHJA and PR1-8 showed 60.98% and 63.22% disease control efficiency, respectively. The control effect of strain GKSHJA with application 24 h before and after inoculation were 55.22% and 16.44%, respectively. The control effect of strain PR1-8 were 51.94% and 24.39% in the greenhouse potted seedlings inoculated with powdery mildew. The preinoculation application of cell free filtrate showed much higher disease control efficiency than postinoculation application. The applications of 5 times diluted cell free filtrates showed 27.81% (in GKSHJA treatment) and 30.19% (in PR1-8 treatment) less disease index than that in untreatment control. In a field experiment, the control effect of biocontrol strains GKSHJA and PR1-8 were 56.33% and 69.88%, respectively, after application of 5 times dilution of cell free filtrate on naturally infected zucchini plants. These results show that strains GKSHJA and PR1-8 are potential biocontrol endophytic actinomycetes to control cucurbit powdery mildew and this research has made a solid research foundation for development and application of bio-pesticides on cucurbits powdery mildew.